1. Field of the Invention
The present invention relates to a charged particle beam apparatus, such as a focused ion beam apparatus and a scanning electron microscope.
2. Description of the Related Art
A focused ion beam (FIB) apparatus is known as an apparatus for processing and observing a minute sample such as a semiconductor device. Further, an FIB-SEM composite apparatus is known as an apparatus for observing a sample under processing by a focused ion beam in real time through a scanning electron microscope (SEM).
In general, in the FIB-SEM composite apparatus, an FIB column and an SEM column are arranged so that an irradiation axis of the FIB column and an irradiation axis of the SEM column may form an angle of about 50° to 60° therebetween. With this arrangement, the same region of the sample can be observed by the FIB and the SEM. The FIB-SEM composite apparatus displays an observation image so that the same observation target may be displayed in an FIB image and an SEM image while having the same perpendicular direction.
For example, as illustrated in FIG. 5A, the FIB-SEM composite apparatus irradiates a lamellar sample 24 fixed on a sample holder 23 with an ion beam 51 and an electron beam 52, to thereby acquire observation images. An SEM image 55 on the left of FIG. 5B and an FIB image 56 on the right of FIG. 5B are the acquired observation images. The SEM image 55 and the FIB image 56 are displayed so that an observation plane 24a of the lamellar sample 24 has the same perpendicular direction. Accordingly, the positional relationship of the lamellar sample 24 observed through the SEM image 55 and the FIB image 56 is made clear, and it is therefore easy for an operator to operate.
By the way, along with the reduction in device dimensions in recent years, it is requested to perform high-resolution SEM observation on a sample surface processed by the FIB. Then, a composite charged particle beam apparatus in which an FIB column and an SEM column are orthogonally arranged is proposed (see Japanese Patent Application Laid-open No. 6-231720).
This apparatus can perform SEM observation on a cross-section processed by the FIB from the perpendicular direction. In general, the SEM can observe an observation plane from the perpendicular direction at a high resolution. Therefore, with the apparatus of Japanese Patent Application Laid-open No. 6-231720, the cross-section processed by the FIB can be observed by the SEM in-situ at a high resolution.
However, in the apparatus of Japanese Patent Application Laid-open No. 6-231720, the FIB column and the SEM column are orthogonally arranged, and hence the sample surface observed by the FIB cannot be observed by the SEM. Therefore, there has been a problem in that it is difficult for the operator to grasp the positional relationship of the sample in an observation image.